Saw a daughter get mature (5)
I believe the answer is:
adage
'saw' is the definition.
('adage' can be a synonym of 'saw')
'a daughter get mature' is the wordplay.
'a daughter' becomes 'ad' (I've seen this in other clues).
'get' means one lot of letters go next to another.
'mature' becomes 'age' ('age' can be a synonym of 'mature').
'ad'+'age'='ADAGE'
(Other definitions for adage that I've seen before include "Dictum" , "Slogan" , "Old saying, maxim" , "Old saw" , "Short statement expressing a general truth" .)